You do the workout as hard as you can for 20 seconds, then rest for 10 seconds. This definitely gets your heart rate up as well as your improving upper body strength and your core.

Repeat 2 times: You will need a stop watch

00:00 SQUAT THRUST

00:20 REST

00:30 MOUNTAIN CLIMBER

00:50 REST

1:00 HIGH KNEES

1:20 REST

1:30 JUMPING JACKS

1:50 REST

One study group did the 4 minute workout and another study group did 40 minutes of running. After 6 months, the 4 minute group had increased their cardiovascular health a bit more than those who ran 40 minutes each day.